Atlantic City massacre

The Atlantic City massacre was a helicopter attack on a meeting of the Commission of the American Mafia at the Palazzo Azzurro in Atlantic City, New Jersey in 1979. The attack was planned by Don Osvaldo Altobello (boss of the Tattaglia crime family) and Don Licio Lucchesi (a powerful mafioso from Italy), as they supported Corleone crime family street boss Joey Zasa in his rivalry with Don Michael Corleone (who was trying to take over International Immobiliare). The result was the deaths of twelve people and ten more being injured.

Background
Michael Corleone, boss of the Corleone crime family, oversaw the legitimization of his family's businesses during the 1960s and 1970s, entrusting the family's illegal activities to Joey Zasa, the family's "street boss" in New York City. Corleone kept Zasa at arm's length, but Zasa held a large degree of autonomy, hiring African-Americans and Hispanics into his family, as well as selling drugs on the streets. It was even rumored that Zasa was disrespecting Don Corleone behind his back, knowing that he had little control over him.

By 1979, Corleone had decided to sell all of his shares in the casino business and move into real estate, with Corleone and his lawyer B.J. Harrison arranging for Corleone to buy shares in Internazionale Immobiliare, an international real estate company. Corleone, who was awarded the Order of St. Sebastian by the Catholic Church, met with Archbishop Liam Gilday to discuss the move. In exchange for Corleone paying $600 million to help the Vatican Bank pay off much of its deficit, he would be given shares in the company, including the Vatican's 25% share. Immobiliare's board quickly approved the offer, awaiting ratification from the ill Pope Paul VI.

The Immobiliare scheme, however, was an elaborate swindle conspired by Italian mafioso Licio Lucchesi, Vatican accountant Friedrich Keinszig, and Archbishop Gilday, who sought to have Corleone pay off the Vatican Bank's debt before delaying his acquisition of Immobiliare (the Pope's ill health prevented him from authorizing the deal) until he could be taken care of. This would be handed by Corleone's friend and fellow mob boss Osvaldo Altobello (boss of the Tattaglia crime family), who persuaded Zasa to seize power for himself.

Zasa, who was rivals with Corleone's nephew Vincent Mancini, was unpopular both in New York and on The Commission, as he was criticized for failing to prevent the spread of drugs on the streets, and for being out-of-control. Altobello and Zasa plotted to wipe out The Commission when a meeting was called at the Palazzo Azzurro in Atlantic City, with Zasa hoping to wipe out the old order, bring in the new order, and gain respect and power among them. Zasa arranged for hitmen in a helicopter to attack the meeting after both he and Don Altobello left.

The meeting
Don Corleone hosted the meeting on the top floor of the hotel, where he announced that he was dissolving his partnerships in the casino business with his fellow bosses, and that he was going to deliver them their shares and interest payments immediately. Every boss except for Zasa received money, leading to Zasa speaking up about how he had been treated with no respect, and about how he had worked hard so that everyone else could make money. He then stormed out, with Don Altobello following him, ostensibly to reason with him. Just as the dons began to talk amongst themselves again, the tables began to shake as the sound of helicopter rotors grew, and Mancini warned Don Corleone that it was a hit. The helicopter gunmen proceeded to spray the room with fire, hitting several bosses and their bodyguards. Corleone escaped with the help of Mancini. 12 died and 10 more were injured, and the bosses who survived made deals with Zasa.

Aftermath
Don Corleone respected Zasa's action, saying that it was natural for the new to overthrow the old, and he wanted to continue doing business with Zasa. Corleone also realized that Don Altobello was the mastermind behind the attack, but, before he could do anything in response, he had a diabetic stroke and was hospitalized. Al Neri and Connie Corleone, Michael's two trusted lieutenants, gave the hot-headed Mancini the go-ahead for a hit on Zasa, who was assassinated at the Feast of San Gennaro parade on 19 September 1979.